Abrasive machine



Dec. 6, 1960 R. F. PENDERGAST ABRASIVE MACHINE 2 Sheets-Sheet 1 Filed Dec. 15, 1958 INVENTOR.

BY m WA T T ORNE YS Dec. 6, 1960 R. F. PENDERGAST 2,962,842

ABRASIVE MACHINE Filed Dec. 15, 1958 2 Sheets-Sheet 2 INVENTOR. L

RAYMOND E'PENDEROAST BY Y ATTORNEYS Unite ABRASIVE MACHINE Filed Dec. 15, 1958, Ser. No. 780,316

Claims. (Cl. 51-141) My invention relates generally to abrasive machines, and more specifically to abrasive machines of the type employing an endless abrasive band entrained over spaced rolls for the purpose of imparting a smooth finish to flat surfaces of a workpiece.

7 An important object of my invention is the provision of an abrasive machine having a novel arrangement whereby the single endless abrasive belt is utilized to make both a relatively deep initial cut and a second relatively fine finishing cut on the surface of a workpiece during a single pass of the workpiece through the machine. To this end I provide a pair of spaced parallel contact rolls over which said endless abrasive belt is entrained, said rolls being so disposed that portions of the belt running thereover successively engage the surface of the workpiece to be abraded during movement of the workpiece through the machine, at least the first one of said rolls having a flexible resilient peripheral surface formed to provide a i tes atent plurality of circumferentially spaced radially outwardly opening grooves extending at oblique angles to the direction of travel of the workpiece, one side of each of said grooves and the adjacent peripheral surface portion of the grooved contact roll defining relatively sharp leading edges underlying the abrasive belt and causing the portions of the belt overlying said leading edges to cut into the Workpiece substantially in the manner of cutting teeth.

Another object of my invention is the provision of a machine of the type set forth wherein both of said contact rolls have flexible resilient peripheral surfaces which define radially outwardly opening grooves that extend helically thereof, the grooves of the first contact roll having a lead angle greater than the lead angle of the grooves in the second contact roll, and wherein the grooves of the first contact roll are of greater width than those of the second contact roll.

The above, and still further highly important objects and advantages of my invention, will become apparent from the following detailed specification, appended claims and attached drawings.

Referring to the drawings, which illustrate the invention, and in which like reference characters indicate like parts throughout the several views:

Fig. 1 is a view in side elevation of an abrasive machine built in accordance with my invention;

Fig. 2 is a view in front elevation, as seen from the line 2-2 of Fig. 1, on a reduced scale, some parts being broken away;

Fig. 3 is an enlarged view" in section, taken substantially on the line 3-3 of Fig. 2;

Fig. 4 is an enlarged fragmentary view corresponding to a portion of Fig. 3;

Fig. 5 is a fragmentary view in front elevation of one of the contact rolls of my invention; and

Fig. 6 is a fragmentary view in front elevation of the other contact roll of my invention.

In the preferred embodiment of my invention illustrated, a supporting frame structure is indicated in its entirety by the numeral 1, said frame structure compris- 2,962,842 Patented Dec. 6, 1960 from the front to the rear thereof, the workpiece 10 being in the nature of a section of flat stock of wood, metal or any material on which it is desired that the machine operate.

A workpiece engaging and feeding roll 11 is keyed or otherwise rigidly mounted on a shaft 12 that is journalled in bearings 13, one of which is shown, said bearings each mounted on a different one of a pair of mounting arms 14 which extend generally longitudinally of the direction of movement of the workpiece 10, and which are mounted at their rear ends to a shaft 15 journalled in bearings 16 that are mounted on the side frame members 2 and 3. The shafts 12 and 15 are disposed on axes parallel to the axes of the shafts 8 and 9. The front ends of the arms '14 define head portions 17 for reception of adjustment screws 18 that are adjustably locked in place by suitable lock nuts 19. The lower ends of the adjustment screws 18 engage pads 20 on the top surfaces of the side frame members 2, to limit downward swinging movement of the arms 14 and parts carried thereby.

The mounting arms 14 further carry a pair of guide rolls 21 and 22 that are mounted on shafts 23 and 24 respectively, these shafts at their opposite end portions being mounted in slide blocks 25 and 2-5 respectively. These slide blocks are mounted for sliding engagement in respective pairs of guide brackets 27 and 28, the brackets of each pair thereof being mounted on each of the mounting arms 14. Adjustment screws 29 and 30 are operatively coupled to respective guide brackets 27 and 28, and to respective slide blocks 25 and 26, in the usual manner, to raise and lower their respective guide blocks and guide rolls 21 and 22 with respect to the mounting arms 14. With reference to Figs. 1 and 3, it will be seen that the rear guide roll 22 directly overlies the rear supporting roller 7, the front guide roll 21 being disposed intermediate the rear guide roll 22 and the feeding roll 11. Preferably, and as shown, the axes of the guide rolls 21 and 22 are parallel to the axes of the feeding roll 11 and supporting rollers 6 and 7. With reference to Fig. 2, it will be noted that the shaft 12 of the feeding roll 11 is extended to receive thereon a pulley 31 over which runs a pair of drive belts 32 which may be assumed to be entrained over another pulley not shown but operatively coupled to a conven tional drive motor or the like, also not shown, whereby the workpiece feeding rotation is imparted to the feeding roll 11 in a clockwise direction with respect to Figs. 1 and 3.

A sub-frame 33 is mounted in the frame structure 1 by means of a transverse mounting shaft 34, one end of which extends through a suitable aperture in the side frame member 3, as indicated at 35 by dotted lines in Fig. 2, the opposite end portion of the shaft 34 being supported by a cradle-like bearing 36 on a mounting plate 37 that is pivotally mounted to the side frame member 2, by means of aligned pivot bolts or the like 38, see Fig. 1. At its front end, the sub-frame 33 is provided with a pair of bearings 39 which journal a rotary shaft 40 that extends through a suitable opening 41 through the side frame member 3, as indicated at 41 by dotted lines in Fig. 2 Outwardly of the side frame members 3, the shaft 40 is provided with a pulley 42 over which is entrained a pair of drive belts or the like 43 which runover a drive pulley 44 fast on the shaft 45 of a conventional drive motor 46, see Fig. 2. The opposite end portion of the shaft 40 is received in a cup-like bearing 47 in the mounting plate 37, the bearing 47 and the opening indicated at .41, sup p,or,ting the front .endportion of the sub-frame 33 through the. medium ofthe shaft 40.

.Keyed or otherwise rigidly mounted on the shaft 40, between the bearings 39 in the sub-frame 33, is a first contact roll 48 directly underlying the feeding roll 11 the axis of the shaft 40 being parallel to the axis of the shaft12 of the feeding roll 11. Preferably, the outer circumferential surface of the roll 48 is covered with a layer or tire 49 of flexible resilient material such as rubber or the like. The outer cylindrical surface50 of the tire 49 is provided with a plurality of circumferentially spaced radially outwardly opening grooves or channels 51 which extend in directions helically of the contact roll 48, one side 52 of each of the grooves 51 cooperating with the adjacent cylindrical surface portion 50 to define a leading edge 53, see particularly Fig. 4.

A second contact roll 54 comprises a cylindrical drum 55 and an outer layer or tire 56 of flexible resilient material, similar to the tire 49. Like the contact roll 48, the outer peripheral surface 57 of the contact roll 54 is provided with a plurality of radially outwardly opening helically extending grooves 58, one side of each of which operate with an adjacent outer cylindrical surface portion 57 to define a sharp leading edge 59. The second contact roll 54 is mounted on a shaft 60 that is journalled at its opposite ends in bearings 61 which are mounted on supporting brackets 62 bolted or otherwise rigidly secured to opposite sides of the sub-frame 33, as indicated at 63. The second contact roll 54 rotates on an axis parallel to the axis of the first contact roll 48, and directly underlies the guideroll 21, as clearly shown in Figs. 1 and 3.

The rear end portion of the sub-frame 33 defines a pair of laterally spaced rearwardly projecting arms 64 which journal opposite ends of a shaft 65 on which is mounted, between the arms 64, an idler roll 66, the axis of which is parallel to the axes of the first and second contact roll 43 and 54 respectively. An endless flexible abrasive belt 67 is entrained over the first and second contact rolls 48 and 54 respectively and the idler roll 66, said abrasive belt being shown in Figs. 2 and 4 as having abrasive particles adhered to the outer surface thereof. A rotary cleaning brush or the like 68 is mounted on a transverse shaft 68 that is journalled at its opposite end portions in the side frame members 2 and 3, the brush 68 making contact with the outer abrasive surface of the belt 67 between the second contact roll 54 and the idler roll 66, for the purpose of removing particles of material from the workpiece which may have adhered to the abrasive surface of the belt 67.

The first contact roll 48 and the second contact roll 54, rearwardly thereof, are so disposed, that the abrasive belt 67 is caused to engage the under surface of the workpiece 10 as it passes over the first contact roll 48 and again as it passes over the second contact roll 54. The grooves 51 in the tire of the first contact roll 48 cause minute, almost invisible ridges to be formed on the overlying portions of the abrasive belt 67, which ridges cause the abrasive material to bite into the under surface of the workpiece 10 more deeply than would otherwise occur in the absence of the grooves 51. Assuming that the directionof rotation of the contact rolls 48 and 54 is counterclockwise with respect to Figs. 1, 3, and 4, the abovementioned ridges are most prominent over the leading edges 53 and 59 of the first and second contact rolls 48 and 54 respectively, due to the tension of the belt 67 and the slight pressure exerted by the contact rolls against the under, surface of the workpiece 10. Obviously, if rotation is imparted to the contact rolls 48 and 54 and the idler roll 66 in a clockwise direction with respect to Figs. 1, 3, and 4, the Opposite sides of the grooves 51 and 58 would cooperate with their respective peripheral surface portions and 57 todefinethe leading edges of saidgrooves. Inasinuchas the grooves 51 in the first contact roll 48 are of much greater width than thegrooves 58 in the second contact roll 54, the deeper or coarser bite of the abrasive particles on the abrasive belt 67 is made between the first contact roll 48 and the overlying feeding roll 11, the smoother finishing cut being made on the under surface of the workpiece 10 betweenthe second contact roll 54 and the overlying guide. roll 21. The, difference in cut caused by the two contact rolls 48 and54 is further influenced by-the ditference'between thelead' angles of the grooves 51 and 58, these lead. anglesbeing. the angles between the leads of the grooves and the planes perpendicular to the axes of the respective contact rolls. For the purpose of the present example, the lead angle of the grooves 51 of the first contact roll 48 is substantially 45, while that of the grooves 58 of the second contact roll 54 is 25, see Figs. 5 and 6. In practice, I have found that, the greater the lead angle,.the greater or coarser'the depth of cut in the workpiece and, if desired, the second contact roll 54 may be smooth and devoid of grooves altogether. However, with the above-described apparatus and arrangement of first and second contact rolls, as set forth, I have been able to remove rough surface portions from the workpiece and obtain a very finefinish thereon with the use of a single grade of abrasive belt and with but a single pass of the workpiece 10 through the machine. Further, while I have shown the contact rolls as rotating in a counterclockwise direction with respect to Figs. 1, 3 and 4, to cause the workpiece engaging portion of the abrasive belt 67 to move in the direction of feed of the workpiece 10, it will be appreciated that satisfactory results can be obtained by rotating the contact rolls in the opposite direction.

My novel abrasive machine has been thoroughly tested and found to be completely satisfactory for the accomplishment of the objectives set forth; and, while I have shown and described a preferred embodiment of my abrasive machine, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention, as defined in the claims.

What I claim is:

1. In an abrasive machine, a frame structure, means on said frame structure for supporting and feeding a workpiece in a given direction, a first contact roll mounted in spaced relation to the workpiece supporting and feeding means for rotation on an axisextending generally transversely of the direction of movement of said workpiece, a second contact roll mounted in said frame structure in rearwardly spaced relation to said first contact roll for rotation on an axis parallel to the axis of said first contact roll, an endless abrasive belt entrained over said contact rolls and adapted to engage a surface of said workpiece, and means for imparting movement to said feeding means to feed the workpiece in a direction from said first contact roll toward the second contact roll and for imparting rotation to one of said contact rolls to cause travelling movement to be imparted to said abrasive belt, the outer cylindrical surface ofsaid first contact roll having circumferentially spaced radially outwardly opening grooves extending helically thereof, said grooves having side wall surfaces cooperating with adjacent cylindrical surface portions of said first contact roll to define relatively sharp leading edges extending continuously and uninterruptedly from one end of said first contact roll to the other end thereof.

2. In an abrasive machine, a frame structure, means on.

said frame structure for supporting and feeding a workpiece in a given direction, a first contact roll mounted in spaced relation to the workpiece supporting and feeding means for rotation on an axis extending generally transversely of the direction of movement of said workpiece, a second contact roll mounted in said frame structure in rearwardly spaced relation to said first contact roll for rotation on an axis parallel to the axis of said first contact, roll, an endless abrasive belt entrained over.

said contact rolls and adapted to engage a surface of said workpiece, and means for imparting movement to said feeding means to feed the workpiece in a direction from said first contact roll toward the second contact roll and for imparting rotation to said contact rolls, said contact rolls having cylindrical surfaces and spaced grooves in said cylindrical surfaces, said grooves extending helically thereof and having side wall surfaces cooperating with adjacent cylindrical surface portions of their respective contact rolls to define relatively sharp leading edges extending continuously and uninterruptedly from one end of their respective contact rolls to the other end thereof, the grooves in said first contact roll being of greater width than those of said second contact roll.

3. In an abrasive machine, a supporting frame structure, means on said frame structure for supporting and feeding a workpiece in a given direction, a first contact roll mounted in said frame structure in spaced relation to the workpiece supporting and feeding means for rotation on an axis extending generally transversely of the direction of movement of said workpiece, a second contact roll mounted in said frame structure in rearwardly spaced relation to said first contact roll for rotation on an axis parallel to the axis of said first contact roll, an endless abrasive belt entrained over said contact rolls and adapted to engage a surface of said workpiece, and means for imparting movement to said feeding means to feed the workpiece in a direction from said first contact roll toward the second contact roll and for imparting rotation to said contact rolls in a work feeding direction and at a higher rate of peripheral speed than that of said feeding means, said contact rolls having flexible resilient peripheral surfaces and spaced grooves in said peripheral surfaces, said grooves extending helically thereof and having side wall surfaces cooperating with adjacent peripheral surface portions of their respective contact rolls to define relatively sharp leading edges extending continuously and uninterruptedly from one end of their respective contact rolls to the other end thereof, the grooves in said first contact roll being of greater width than those of second contact roll.

4. In an abrasive machine, a supporting frame structure, means on said frame structure for supporting and feeding a workpiece in a given direction, a first contact roll mounted in said frame structure in spaced relation 4 to the workpiece supporting and feeding means for rotation on an axis extending generally transversely of the direction of movement of said workpiece, a second contact roll mounted in said frame structure in rearwardly spaced relation to said first contact roll for rotation on an axis parallel to the axis of said first contact roll, an endless abrasive belt entrained over said contact rolls and adapted to engage a surface of said workpiece, and means for imparting movement to said feeding means to feed the workpiece in a direction from said first contact roll toward the second contact roll and for imparting rotation to said contact rolls, said contact rolls having flexible resilient peripheral surfaces and spaced grooves in said peripheral surfaces, the grooves of said contact rolls extending helically thereof, the grooves in said first contact roll having a lead angle greater than the lead angle of the grooves in said second contact roll and being of greater width than the grooves in said second contact roll.

5. In an abrasive machine, a supporting frame structure, means on said frame structure for supporting and feeding a workpiece in a given direction, a first contact roll mounted in said frame structure in spaced relation to the workpiece supporting and feeding means for rotation on an axis extending generally transversely of the direction of movement of said workpiece, a second contact roll mounted in said frame structure in rearwardly spaced relation to said first contact roll for rotation on an axis parallel to the axis of said first contact roll, an endless abrasive belt entrained over said contact rolls and adapted to engage a surface of said workpiece, and means for imparting movement to said feeding means to feed the workpiece in a direction from said first contact roll toward the second contact roll and for imparting rotation to said contact rolls, said contact rolls having flexible resilient peripheral surfaces and spaced grooves in said peripheral surfaces, the grooves of said contact rolls extending helically thereof, the grooves in said first contact roll having a lead angle of approximately the lead angle of said grooves in the second contact roll having a lead angle of approximately 25, the grooves in said first contact roll being of greater width than the grooves of said second contact roll.

References Cited in the file of this patent UNITED STATES PATENTS 348,177 Totman Aug. 24, 1886 637,121 Huseby Nov. 14, 1899 1,043,194 Blewney Nov. 5, 1912 2,162,279 Herchenrider June 13, 1939 2,581,270 McVey Jan. 1, 1952 

